Conventional flat panel displays, such as thin film transistor liquid crystal displays (TFT-LCD), generally use cold negative electrode fluorescent lamps (CCFLs) as their backlights. CCFLs generally have high luminance and uniform brightness.
However, a CCFL needs to use a high-voltage driving circuit electrically connected to both two ends of the CCFL to drive the CCFL to emit light. The high-voltage driving circuit mainly includes an integrated power board (IPB) and a balance board. The IPB provides a high-voltage alternating current (AC) power supply to the balance board, and the balance board converts the high-voltage AC power supply to a group of AC output power supplies with same phases for driving the CCFLs. However, due to effect of characteristics of CCFLs, the method of using the AC output power supplies with the same phases for driving CCFLs results in generating abnormal water ripple images on the displays, and therefore makes users' eyes feel uncomfortable.
A conventional method for overcoming above shortcomings is adding another high-voltage AC power supply, which provides another group of AC output power supplies with phases that are different to (e.g., reverse to) the phases of aforementioned group of AC output power supplies, to the IPB. Both the two high-voltage AC power supplies are provided to the balance board. The balance board converts the two high-voltage AC power supplies to two groups of AC output power supplies, respectively, wherein phases of the two groups of AC output power supplies are different to (e.g., reverse to) each other. Thus, the two groups of AC output power supplies are both used to drive a CCFL to prevent the abnormal water ripple images from being generated. A disadvantage of the conventional method is that adding another high-voltage AC power supply to the IPB causes cost of the high-voltage driving circuit to increase. Therefore, how to overcome the shortcomings of above conventional high-voltage driving circuit, and provide a high-voltage driving circuit that is easy to manufacture, is an object pursued by industry.